1. Field of the Invention
This invention relates to communication connectors that are configured to compensate for crosstalk produced between different signal paths through the connector.
2. Discussion of the Known Art
There is a need for a durable, high-frequency communication connector assembly that compensates for (i.e., cancels or reduces) crosstalk produced between different signal paths carried through the connector. As defined herein, crosstalk occurs when signals conducted over a first signal path, e.g., a pair of terminal contact wires associated with a communication connector, are partly transferred by inductive or capacitive coupling into a second signal path, e.g., another pair of terminal contact wires in the same connector. The transferred signals define "crosstalk" in the second signal path, and such crosstalk degrades any signals that are being routed over the second path.
For example, an industry type RJ-45 communication connector typically includes four pairs of terminal wires defining four different signal paths. In the conventional RJ-45 plug and jack connectors, all four pairs of terminal wires extend closely parallel to one another over the lengths of the connector bodies. Thus, signal crosstalk may be induced between and among different pairs of terminal wires, particularly in a mated RJ-45 plug and jack combination. The amplitude of the crosstalk becomes stronger as the coupled signal frequencies or data rates increase.
Applicable industry standards for rating the degree to which communication connectors exhibit crosstalk, do so in terms of near-end crosstalk or "NEXT". Moreover, NEXT ratings are typically specified for mated plug and jack combinations, wherein the input terminals of the plug connector are used as a reference plane. Communication links using unshielded twisted pairs (UTP) of copper wire are now expected to support data rates up to not only 100 MHz or industry standard "Category 5" performance, but to meet proposed "Category 6" performance levels which call for at least 46 dB crosstalk loss at 250 MHz.
U.S. Pat. No. 5,186,647 to Denkmann, et al (Feb. 16, 1993), which is assigned to the assignee of the present invention and application, discloses an electrical connector with crosstalk compensation for conducting high frequency signals. The connector has a pair of metallic lead frames mounted flush with a dielectric spring block, with connector terminals formed at opposite ends of the lead frames. The lead frames themselves include flat elongated conductors each of which includes a spring terminal contact wire at one end for contacting a corresponding terminal of a mating connector, and an insulation displacing connector (IDC) terminal at the other end for connection with an outside insulated wire lead. The lead frames are placed one over the other on the spring block, and three conductors of one lead frame have cross-over sections formed to overlap corresponding cross-over sections formed in three conductors of the other lead frame. All relevant portions of the '647 patent are incorporated by reference herein. U.S. Pat. No. 5,580,270 (Dec. 3, 1996) also discloses an electrical plug connector having crossed pairs of contact strips.
Crosstalk compensation circuitry may also be provided on or within layers of a printed wire board, to which spring terminal contact wires of a communication jack are connected within the jack housing. See U.S. patent application Ser. No. 08/923,741 filed Sep. 29, 1997, and assigned to the assignee of the present application and invention. All relevant portions of the '741 application are incorporated by reference herein. See also U.S. Pat. No. 5,299,956 (Apr. 5, 1994).
U.S. patent. application Ser. No. 09/264,506 filed Mar. 8, 1999 (now U.S. Pat. No. 6,116,964 issued Sep. 12, 2000), and assigned to the assignee of the present invention and application, discloses a communication connector assembly having generally co-planar terminal contact wires. Certain pairs of the contact wires have opposed cross-over sections near their line of contact with a mating connector, and a coupling region along the wires beyond the cross-over sections compensates for crosstalk introduced by the mating connector. All relevant portions of the '506 application are also incorporated by reference herein.
In the connector assembly of the above '506 application, the terminal contact wires have base portions that enter a wire board alternatingly along two rows which are perpendicular to the direction of the contact wires, thus defining a staggered wire board entry pattern or "footprint". Coupling of a polarity opposite to that needed for crosstalk compensation may be introduced among the base portions of the contact wires, however, and the amount of crosstalk compensation needed elsewhere (e.g., on the wire board) to achieve Category 6 performance may need to be increased as a result.
A so-called "MAX 6" modular jack outlet available from The Siemon Company has a printed wire board and four pairs of contact wires that extend generally normal to the board. No cross-over is formed in any of the wire pairs, and the contact wires enter the wire board along three rows.
A communication jack connector which, when mated with a typical RJ-45 plug, provides such crosstalk compensation that the mated connectors will meet or exceed the proposed Category 6 performance levels, is highly desirable.